Fluorine compounds are extremely important as, for example, functional materials, compounds for medicines and agrochemicals, electronic materials, and other various chemical products, as well as the intermediates of these.
Fluoride, hydrogen fluoride, sulfur tetrafluoride, etc., have been used as fluorinating agents to obtain a target fluorine compound by fluorinating a variety of organic compounds as a starting material. These fluorinating agents, however, are difficult to handle due to, for example, their toxicity, corrosiveness, and explosion risk at the time of reaction, and thus require special devices or techniques.
A reaction for introducing a fluorine atom into an organic compound by using nucleophilic substitution with fluoride ion has recently been developed, in addition to various fluorinating agents used for the reaction.
Iodine pentafluoride (IF5), for example, is known as a powerful fluorinating agent with high oxidizing power; however, this is a dangerous liquid fluorinating agent because it reacts with moisture in air and decomposes while generating HF. Non-patent Literature 1 recently reported that IF5 having such features becomes a stable white solid in air when mixed with pyridine-HF and is effective for fluorination of various sulfur compounds.
Further, bromine trifluoride (BrF3) is a liquid that has oxidizing power stronger than that of IF5. BrF3 is usable in fluorination of various kinds of substrates, and is used, for example, to produce uranium hexafluoride in nuclear fuel processing. However, BrF3 is a toxic and corrosive liquid, and is a strong irritant to the eyes or skin. In air, BrF3 has the problems of decomposing within a short period of time, generating hydrogen fluoride, and the like. Further, BrF3 reacts vigorously with general-purpose solvents, such as methylene chloride, at room temperature. Thus, the solvent used with BrF3 is limited when BrF3 is used as a fluorinating agent. Accordingly, the use of BrF3 requires special knowledge and devices, and the practical use of BrF3 in a wide scope has not yet been achieved at present, although BrF3 has a high reactivity as a fluorinating agent.